You just /join #channel .. if it's empty its yours, some networks have channel servecis, and then you can register the channel in that, but many dont suport this, then the only was is to have a bot holding the channel for you, and bot shells cost money, so the answer is no, it dont cost to have a channel.. it maybe cost to keep it "alive" while you are offline, cos you need somthing or somone idle on it while your offline.. so i guess the best way to hold a channel is to ask a friend that have 24/7 connection to idle on it, then it wont cost you anything..
